A mass is placed on a spring and oscillates with a period of 1 second. Now a heavier mass is placed on the same spring. Which statements are true? I. The heavier mass oscillates with a shorter period because the gravitational force on it is greater. II. The heavier mass oscillates with the same period because gravitational accel eration is constant. = III. The heavier mass oscillates with a longer period because of its greater inertia. IV. The heavier mass must have greater me- chanical energy than the rst because it is heavier. V. The heavier mass must have less me- chanical energy than the rst because it moves more slowly. VI. One cannot reach any conclusion about mechanical energy without knowing the amplitude of motion in each case. 1. I and VI only 2. I and V only 3. II and IV only 4. 1 and IV only 5. III and V only 6. III and IV only 7. III and VI only 8. II and VI only 9. II and V only